20100924 is out now, with a collection of improvements. It's still not much more usable for editing tasks - I'm focusing of fleshing out the structure first. It should start to get more useful once the Python API is enabled (many editing commands, including ctrl+backspace and ctrl+delete rely on this), which I'm currently expecting to happen after projects and session support, which are the next targets.

There's a quick panel in this version, which can be used to switch between open buffers. It works differently to the one in Sublime Text: where as Sublime Text will filter items, X will both filter and reorder them. This makes it much nicer to work with on large projects, which you'll get to see when projects are exposed in the near future. The quick panel itself is still a work in progress - most of the time so far has been spent ensuring that it's fast on large projects (i.e., 50k+ files), and that the ranking gives high quality results.

As an aside, I'm quite happy with the side bar and view resizing in this version - it has detents to help stop the resize at a nice spot (as long as you're not moving the mouse quickly), and the resize areas can be double clicked to resize them directly to the detent.

I'm not sure if you are taking suggestions / ideas, but I was thinking that it might be nice to have the possibility to filter the contents of the side bar (in the case when many files are open or when you only want to consider a subset of the open files). Maybe a keyboard shortcut could give focus to a input box at the top of the side bar and the contents of the side bar would be filtered in the same way as the quick panel (but without the sorting). This would be different than the "Select Buffer" option (using the quick panel) in that the filtered file list in the side bar would persist until the filter was cleared.

I imagine that you will be adding projects (maybe with the latest "session" for that project) to the side panel as a separate top level node (at the same level as "Buffers"). If this is the case, I think it would be helpful to be able to filter the side bar contents, which would allow you to have a view of the matching files across multiple projects or sessions (including the current session).

jbjornson: I was originally considering implementing the quick panel entirely as filtering in the sidebar, but abandoned that in favour of the current approach, so that results could be ranked. I imagine it wouldn't be unhandy to have filtering in the side bar in addition to the quick panel, but the quick panel would generally supersede any side bar filtering?

Actually, there's a good argument to be made for placing the current quick panel in the side bar directly, filtering results with ranking. I'll look into it again when project support is up and running.

jps wrote:jbjornson: I was originally considering implementing the quick panel entirely as filtering in the sidebar, but abandoned that in favour of the current approach, so that results could be ranked. I imagine it wouldn't be unhandy to have filtering in the side bar in addition to the quick panel, but the quick panel would generally supersede any side bar filtering?

I think the quick panel filter would have to supersede any side bar filtering. Maybe you could default the quick panel filter to be the same as any existing sidebar filter and allow the user to edit that filter.